A medical system includes: a treatment instrument having an insertion portion configured by an exterior member, and an insertion member that is inserted into the exterior member and is longer than the exterior member; an insertion portion inserting/pulling-out device to transmit a driving force to the exterior member or the insertion member configuring the insertion portion of the treatment instrument, the insertion portion inserting/pulling-out device advancing/retreating at least one of the exterior member and the insertion member; and a driving force non-transmitting portion provided to the insertion member, the driving force non-transmitting portion preventing a driving force of the insertion portion inserting/pulling-out device from being transmitted to the exterior member when the insertion member is moved by a predetermined distance.